Police are investigating an armed robbery at a fast food restaurant in Sydenham this week.

Investigators believe three men entered the 24 hour restaurant, located at the corner of Calder Park Drive and Melton Highway, armed with an axe, baseball bat and hammer about 2.40am on Wednesday 14 March.

The offenders, all wearing gloves and shirts covering their faces, smashed furnishings in the store before making demands for cash.

The thieves then fled with money from the registers and a handbag and wallet, belonging to staff members.

One of the offenders also allegedly manhandled a staff member in the store during the incident.

He suffered minor redness to his arms.